- Email: [email protected]
Risks to the patient in diagnostic radiology
THE
FACULTY VOL. V I I I
JOURNAL
OF
OF
THE
RADIOLOGISTS
J A N U A R Y , I957
No. 3
EDITORIAL R I S K S TO THE P A T I E N T IN D I A G N O S T I C R A D I O L O G Y EVERY student of radiology or radiography is taught the dangers attendant upon the use for diagnostic or therapeutic purposes of ionizing radiations, but the precautions he is instructed to observe in order to avoid or minimize such dangers are largely directed towards the protection of the medical and technical personnel for whom radiological work constitutes an occupational hazard. Pioneers in the development and application of X rays and radio-active substances suffered injuries of varying severity, many of them ultimately proving fatal. Th ei r names are commemorated in the X-ray Martyrs' Memorial at Hamburg, which stands as much as a tribute to their work as a salutary reminder to their successors of the risks of their calling. In the consideration of the dangers of ionizing radiations to the patient, attention has largely been concentrated on the more intensive radiation given in radiotherapy where it is recognized that the margin between an effective depth dose to the tumour and a destructive dose to the circumstantial tissues is often a narrow one. For the most part the risks to the patient of radiodiagnostic exposures unless prolonged or repeated have been regarded as slight or non-existent, and such risks have been progressively minimized in the last two decades by the combined efforts of radiologists, physicists, radiographers, and designers and manufacturers of apparatus. Since 195o, however, there has been a growing awareness that whilst the dangers inherent in the physical properties of the radiations have been reduced and controlled, the effects on certain tissues and certain types of patients may be enhanced by the particular susceptibility of such tissues or patients. T h e problem is twofold--the present damage which may be caused in man and the possible genetic harm to future generations--and in the industrial age of to-day must needs be considered in relation to the increasing radiations received from other sources. For no longer are the medical and allied professions the only or indeed the principal workers in the field of ionizing radiations. In the recent report of the Chief Inspector of Factories for i955 it is estimated that at least 535 factories in the United Kingdom are using ionizing radiations. In endeavouring to assess the total effect on the whole population of ionizing radiations, the fall-out from nuclear test explosions, the disposal of waste from reactors making fission products, and even the excreta from patients treated by radio-active isotopes have to be considered. It is clear then that the use of X rays for diagnostic or therapeutic purposes should be undertaken with the knowledge that they contribute to the total irradiation of the community which is already cumulative. Added importance has been given to this problem in the past year by the publication of the Medical Research Council Report on The Hazards to M a n of Nuclear and Allied Radiations and of a preliminary communication by Dr. Alice Stewart and her colleagues on " Malignant Disease in Childhood and Diagnostic Irradiation in Utero " (Stewart, Webb, Giles, and Hewitt, 1956). T h e authors of the Medical Research Council Report draw two general conclusions : First, that almost the whole genetically significant dose to the population (from diagnostic radiology) is accounted for by relatively few sites of examinati9n, principally the hip, the lumbar spine, the lower abdomen, and the pelvis. T h e far more frequent examinations of the chest, head, and limbs make relatively unimportant contributions. Secondly, according to the present calculations, the amount of radiation reaching the reproductive organs of the people in this country from diagnostic radiology is as much as az per cent of that derived from natural sources. A more detailed analysis of the subject has been presented by Osborn and Smith (1956). T h e Medical Research Council Report stresses that whilst tissue damage occasioned by radiation may be modified by spreading the dose or by natural healing, the genetic effect or gene mutation caused by irradiating the cells of reproduction is cumulative and irreversible. Th e report calls for a review of medical radio-diagnostic techniques both in regard to their indications and their conditions of performance. Dr. Stewart's report on the possibility of leuk~emia or cancer in the offspring of mothers who have during the relevant pregnancy undergone irradiation for diagnostic purposes is at present incomplete. T h e final publication will be awaited with considerable interest, but meanwhile Io
i46
JOURNAL
OF
THE
FACULTY
OF
RADIOLOGISTS
Dr. Stewart has found evidence that such diagnostic radiology may be at least in part responsible for a proportion of the cases of leuk~emia in children with a peak period in the 3- to 5-year age group. T h e reasons for radiographing these patients have not yet been unequivocally stated and m a y t h e m . selves have a bearing on the subsequent development of leuk~emia, although it has been suggested that they are a n expression of social grading rather than of medical need. Clearly m u c h further work needs to be done before a direct causal relationship is demonstrated between diagnostic radiations and the induction of leuk~emia or of significant gene mutations in man, but the concern of the profession and the public having been aroused it would be unwise not to take this opportunity of reviewing our present methods. T h e increasing d e m a n d for diagnostic radiology in recent years is of multiple causation. In addition to the more ' legitimate ' reasons of increased routine investigations and the extended use of newer techniques, the p u b l i c - - e v e r more conscious of its prescriptive rights u n d e r the National Health S e r v i c e - - i s demanding of its doctors m o r e radiographic examinations, and the importance accorded in the Courts to the f a c t of being X-rayed, as opposed to the value of the findings, frequently compels the y o u n g medical officer to safeguard himself by further adding to their number. Uncritical reading of medical literature often stimulates unreasonable demands on departments of radiology. T h e radiologist should be the arbiter of the n u m b e r and type of radiological examinations of patients referred to him, and it should be his constant concern to eliminate unnecessary projections. As a corollary, every d e p a r t m e n t of radiology ought to be u n d e r the control or subject to the periodic supervision of a consultant radiologist. Records of all radiographic exposures of each patient should be readily accessible, possibly on the outside of the film envelope ; every attempt should be made to reduce radiation in children, pregnant women, and w o m e n in the child-bearing age groups to the m i n i m u m essential for diagnostic purposes. T h e menstrual history might b e taken where appropriate. T h e child of to-day is likely to be subjected as he grows to m u c h more radiation from all sources than his forebears and should be specially protected. Whilst radiography of the chest is a safe procedure, it is w o r t h r e m e m b e r i n g that in a small child the a b d o m e n and pelvis is almost invariably irradiated at the same time as the chest and that a n u m b e r of exposures m a y be made before a satisfactory result is obtained. T h e incidental irradiation of the pelvis during exposures for the upper urinary tract in excretion urography can be avoided by lead rubber protection. Radiography of the opposite joint for comparison with the affected one, especially in the hip, is only justified w h e n it is likely to assist in the making of a difficult diagnosis and not merely to establish a n o r m for the instruction of the medical staff. M a n y routine and follow-up examinations could be eliminated without material disadvantage. Careful preparation of the patient, particularly for abdominal radiography, reduces the necessity for repeat exposures. A b o v e all, obstetric radiology should be undertaken only w h e n its diagnostic advantages clearly outweigh any potential dangers to the foetus. Experienced radiologists in this field consider that certain views of the brim in pelvimetry should be avoided completely. Binks (1955) has suggested that " the ideal to aim at in the case of patients undergoing X-ray diagnostic examinations is to keep the doses down to levels comparable with those r e c o m m e n d e d for persons w h o are occupationally exposed to radiation ". Already radiation is reduced by use of appropriate cones and filters, high kilovoltage where indicated, and fast films. T h e most authoritative guide for all who are concerned with the installation or operation of X-ray apparatus is the revised edition of the Recommendations of the International Commission on Radiological Protection (I955), and therein are listed in broad terms all desirable means of reducing the exposure to diagnostic and therapeutic radiations of the patient, particularly his skin, bloodforming organs, gonads, and eyes. T h i s report also clearly places the overall responsibility for the protection of staff and patients from radiation on the head of the radiological department. T h e whole p r o b l e m of ' r a d i a t i o n h a z a r d s ' is to be discussed at a general meeting of the Faculty of Radiologists at B i r m i n g h a m on Saturday, Feb. 2, 1957. REFERENCES BINKS, W. (I955) , Brit. J. Radiol., 28, 654. MEDICAL RESEARCHCOUNCIL (I956), The Hazards to Man of Nuclear and Allied Radiations, Cmd. 978o, June. London : H.M.S.O. OSBORN, S. B., and SMITH, E. E. (I956), Lancet, I, 949. Recommendations of the International Commission on Radiological Protection (i955) , Supplement No. 6. British Institute of Radiology. STEWART, ALICE, WEBB, J., GILES, D., and HEWITT, D. (I956), Lancet, ~, 447.
FACULTY VOL. V I I I
JOURNAL
OF
OF
THE
RADIOLOGISTS
J A N U A R Y , I957
No. 3
EDITORIAL R I S K S TO THE P A T I E N T IN D I A G N O S T I C R A D I O L O G Y EVERY student of radiology or radiography is taught the dangers attendant upon the use for diagnostic or therapeutic purposes of ionizing radiations, but the precautions he is instructed to observe in order to avoid or minimize such dangers are largely directed towards the protection of the medical and technical personnel for whom radiological work constitutes an occupational hazard. Pioneers in the development and application of X rays and radio-active substances suffered injuries of varying severity, many of them ultimately proving fatal. Th ei r names are commemorated in the X-ray Martyrs' Memorial at Hamburg, which stands as much as a tribute to their work as a salutary reminder to their successors of the risks of their calling. In the consideration of the dangers of ionizing radiations to the patient, attention has largely been concentrated on the more intensive radiation given in radiotherapy where it is recognized that the margin between an effective depth dose to the tumour and a destructive dose to the circumstantial tissues is often a narrow one. For the most part the risks to the patient of radiodiagnostic exposures unless prolonged or repeated have been regarded as slight or non-existent, and such risks have been progressively minimized in the last two decades by the combined efforts of radiologists, physicists, radiographers, and designers and manufacturers of apparatus. Since 195o, however, there has been a growing awareness that whilst the dangers inherent in the physical properties of the radiations have been reduced and controlled, the effects on certain tissues and certain types of patients may be enhanced by the particular susceptibility of such tissues or patients. T h e problem is twofold--the present damage which may be caused in man and the possible genetic harm to future generations--and in the industrial age of to-day must needs be considered in relation to the increasing radiations received from other sources. For no longer are the medical and allied professions the only or indeed the principal workers in the field of ionizing radiations. In the recent report of the Chief Inspector of Factories for i955 it is estimated that at least 535 factories in the United Kingdom are using ionizing radiations. In endeavouring to assess the total effect on the whole population of ionizing radiations, the fall-out from nuclear test explosions, the disposal of waste from reactors making fission products, and even the excreta from patients treated by radio-active isotopes have to be considered. It is clear then that the use of X rays for diagnostic or therapeutic purposes should be undertaken with the knowledge that they contribute to the total irradiation of the community which is already cumulative. Added importance has been given to this problem in the past year by the publication of the Medical Research Council Report on The Hazards to M a n of Nuclear and Allied Radiations and of a preliminary communication by Dr. Alice Stewart and her colleagues on " Malignant Disease in Childhood and Diagnostic Irradiation in Utero " (Stewart, Webb, Giles, and Hewitt, 1956). T h e authors of the Medical Research Council Report draw two general conclusions : First, that almost the whole genetically significant dose to the population (from diagnostic radiology) is accounted for by relatively few sites of examinati9n, principally the hip, the lumbar spine, the lower abdomen, and the pelvis. T h e far more frequent examinations of the chest, head, and limbs make relatively unimportant contributions. Secondly, according to the present calculations, the amount of radiation reaching the reproductive organs of the people in this country from diagnostic radiology is as much as az per cent of that derived from natural sources. A more detailed analysis of the subject has been presented by Osborn and Smith (1956). T h e Medical Research Council Report stresses that whilst tissue damage occasioned by radiation may be modified by spreading the dose or by natural healing, the genetic effect or gene mutation caused by irradiating the cells of reproduction is cumulative and irreversible. Th e report calls for a review of medical radio-diagnostic techniques both in regard to their indications and their conditions of performance. Dr. Stewart's report on the possibility of leuk~emia or cancer in the offspring of mothers who have during the relevant pregnancy undergone irradiation for diagnostic purposes is at present incomplete. T h e final publication will be awaited with considerable interest, but meanwhile Io
i46
JOURNAL
OF
THE
FACULTY
OF
RADIOLOGISTS
Dr. Stewart has found evidence that such diagnostic radiology may be at least in part responsible for a proportion of the cases of leuk~emia in children with a peak period in the 3- to 5-year age group. T h e reasons for radiographing these patients have not yet been unequivocally stated and m a y t h e m . selves have a bearing on the subsequent development of leuk~emia, although it has been suggested that they are a n expression of social grading rather than of medical need. Clearly m u c h further work needs to be done before a direct causal relationship is demonstrated between diagnostic radiations and the induction of leuk~emia or of significant gene mutations in man, but the concern of the profession and the public having been aroused it would be unwise not to take this opportunity of reviewing our present methods. T h e increasing d e m a n d for diagnostic radiology in recent years is of multiple causation. In addition to the more ' legitimate ' reasons of increased routine investigations and the extended use of newer techniques, the p u b l i c - - e v e r more conscious of its prescriptive rights u n d e r the National Health S e r v i c e - - i s demanding of its doctors m o r e radiographic examinations, and the importance accorded in the Courts to the f a c t of being X-rayed, as opposed to the value of the findings, frequently compels the y o u n g medical officer to safeguard himself by further adding to their number. Uncritical reading of medical literature often stimulates unreasonable demands on departments of radiology. T h e radiologist should be the arbiter of the n u m b e r and type of radiological examinations of patients referred to him, and it should be his constant concern to eliminate unnecessary projections. As a corollary, every d e p a r t m e n t of radiology ought to be u n d e r the control or subject to the periodic supervision of a consultant radiologist. Records of all radiographic exposures of each patient should be readily accessible, possibly on the outside of the film envelope ; every attempt should be made to reduce radiation in children, pregnant women, and w o m e n in the child-bearing age groups to the m i n i m u m essential for diagnostic purposes. T h e menstrual history might b e taken where appropriate. T h e child of to-day is likely to be subjected as he grows to m u c h more radiation from all sources than his forebears and should be specially protected. Whilst radiography of the chest is a safe procedure, it is w o r t h r e m e m b e r i n g that in a small child the a b d o m e n and pelvis is almost invariably irradiated at the same time as the chest and that a n u m b e r of exposures m a y be made before a satisfactory result is obtained. T h e incidental irradiation of the pelvis during exposures for the upper urinary tract in excretion urography can be avoided by lead rubber protection. Radiography of the opposite joint for comparison with the affected one, especially in the hip, is only justified w h e n it is likely to assist in the making of a difficult diagnosis and not merely to establish a n o r m for the instruction of the medical staff. M a n y routine and follow-up examinations could be eliminated without material disadvantage. Careful preparation of the patient, particularly for abdominal radiography, reduces the necessity for repeat exposures. A b o v e all, obstetric radiology should be undertaken only w h e n its diagnostic advantages clearly outweigh any potential dangers to the foetus. Experienced radiologists in this field consider that certain views of the brim in pelvimetry should be avoided completely. Binks (1955) has suggested that " the ideal to aim at in the case of patients undergoing X-ray diagnostic examinations is to keep the doses down to levels comparable with those r e c o m m e n d e d for persons w h o are occupationally exposed to radiation ". Already radiation is reduced by use of appropriate cones and filters, high kilovoltage where indicated, and fast films. T h e most authoritative guide for all who are concerned with the installation or operation of X-ray apparatus is the revised edition of the Recommendations of the International Commission on Radiological Protection (I955), and therein are listed in broad terms all desirable means of reducing the exposure to diagnostic and therapeutic radiations of the patient, particularly his skin, bloodforming organs, gonads, and eyes. T h i s report also clearly places the overall responsibility for the protection of staff and patients from radiation on the head of the radiological department. T h e whole p r o b l e m of ' r a d i a t i o n h a z a r d s ' is to be discussed at a general meeting of the Faculty of Radiologists at B i r m i n g h a m on Saturday, Feb. 2, 1957. REFERENCES BINKS, W. (I955) , Brit. J. Radiol., 28, 654. MEDICAL RESEARCHCOUNCIL (I956), The Hazards to Man of Nuclear and Allied Radiations, Cmd. 978o, June. London : H.M.S.O. OSBORN, S. B., and SMITH, E. E. (I956), Lancet, I, 949. Recommendations of the International Commission on Radiological Protection (i955) , Supplement No. 6. British Institute of Radiology. STEWART, ALICE, WEBB, J., GILES, D., and HEWITT, D. (I956), Lancet, ~, 447.